Centralized traffic controlling system for railroads



F. w. BRIXNER ,1 ,040

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed Dec. 30, 19364 Sheets-Sheet 1 Oct. 10, 1939.

.GQZQ 120m v1 3 2 Q Y R 29$ m 1T R m 2 n w m QQ W W 3 (U l T m A hm u 3m 3% H 3 7 AR! v 25 um 2 v Oct. 10, 1939. F. w. BRIXNER CENTRALIIZEDTRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed Dec. 50, 1936 4Sheets-Sheet 2 mcoq .6 tozn 2 S 09 mac .0 toxn 292. m io ATTORNEY Q2 5 ws a Patented Oct. 10, 1939 UNITED STATES PATENT ()FFICE OENTRALIZEDTRAFFIC CONTROLLING SYSTEM FOR RAILROADS Application December 30, 1936,Serial No. 118,337

7 Claims.

This invention relates to centralized traffic controlling system forrailroads, and it more par ticularly pertains to the communication partof such systems.

The present invention contemplates a centralized trafiic controllingsystem in which communication is established between a control ofiiceand a large number of outlying field stations by means of acommunication system of the twowire selective coded simplex type. Theswitches and signals at a plurality of stations located along therailroad track are controlled from the control ofiice by the codedimpulses applied to the two-wire line circuit. 7

The switches and signals are under the supervision of the operator atthe control ofiice so that the condition of such switches, signals andvarious other traffic controlling devices at the distant stations willbe transmitted to the control oifice for providing the operator with thenecessary information for governing train movements. In a system of thistype, a series of impulses forming a particular code combination istransmitted over the line circuit for the selection of a particularfield station and the transmission of controls to the selected station.

Similarly, a series of impulses forming a particular code combination istransmitted over the line circuit for the registration of a fieldstation in the control office and the transmission of indications fromthe sending station. The control and'indication circuits aresointerrelated in the system that controls and indications are transmittedon separate cycles of operation, in other .WOldS, the system is of thesimplex type. Since the present invention is more particularly directedto outbound code transmission, that is, the trans-- mission of controlcodes, and since numerous forms of indication transmission may be usedin the present system, the drawings and the description will be limitedto the control functions of centralized trafiic controlling system.

The circuits are so organized, that, during a control cycle, the controloffice acts as the driver of the system, placing the proper polarityfrom a control office line battery on the line circuit and creating longand short energized and deenergized portions at each step of the system,as.

time they will be executed, provided the station has been selectedduring this cycle.

In the present system, polar impulses are used for station selection,that is, each energization of the line is positive or negative. Forfunction control the capacity of the system is increased by making theenergized periodof a step either long or short, thus giving a choice oftwo for each energized period and thedeenergized period for each step ismade either long or short, thus giving a choice of .two more for eachstep. These four combinations, plus the choice of two provided by thepositive or negative line energization for each step, gives a totalcapacity of six code combinations for each step of the system. c

The polarity of the impulses during the transmission of controls isdetermined in the control ofiice by reversibly connecting the linebattery to the line circuit. The control ofilce acts as the driver orthe impulser, and makes the impulse or energized portion of the impulseseither long or short, as well as making the deenergized or time spaceportion of the impulses either long or short.

The above mentioned characteristic features and additional features ofthe present invention will be explained more in detail in the followingdescription and various advantages of the invention will be inpartpointed out and in part apparent as the descriptionprogresses.

In describing the invention in detail reference will be made to theaccompanying drawings which illustrate one method of carrying out theinvention by way of example. The drawings illustrate, in adiagrammaticmanner, the apparatus and circuits employed" and forconvenience in describing the invention in detail those parts havingsimilar features and functions are designated in the various views bylike letter reference characters, generally made distinctive either byreason of distinctive exponents representative of their location in thesystem or by reason of distinctive preceding numerals representative ofthe order of their operation and in which:--

Figs. 1A and 1B placed end to end in the order named and withcorrespondingly numered lines in alignment, illustrate in schematic formthe apparatus and circuit arrangements employed at a typical controloflice embodying the present invention.

Figs. 2A and 2B placed end to end in'the order named and withcorrespondingly numbered lines in alignment, illustrate the'apparatusand circuit arrangment employed at a typical field station embodying thepresent invention.

The illustrations in the drawings are schematic 55 and abbreviated forthe purpose of clearness and simplicity. In following the detailedoperation of the system for the transmission of controls, Fig. 2A shouldbe placed to the right of Fig. 1B with the line and return conductors inalignment.

The arrangement of those parts of the system which are not illustratedin the drawings and their cooperation with the illustrated portions willbe set forth in the following general description. After the generaldescription a detailed analysis of the transmission of controls from thecontrol oflice will be given.

GENERAL DESCRIPTION The symbols and are employed to indicate thepositive and negative terminals respectively of suitable batteries orother sources of direct current and the circuits with which thesesymbols are used always have current flowing in the same direction, thatis, from to outside of the battery itself.

For convenience in describing the operation of the system the two linewires connecting the control office with the stations are identified byreferring to them as the line and return conductors. These twoconductors extend in series through all of the field stations and arenormally connected together at the end station by means of back contact200 of relay L0 illustrated in the upper right hand portion of Fig. 2B.

In considering the organization of the line circuit, it will beunderstood that additional field stations may be connected in seriestherewith, between the control office and the illustrated station orbetween the illustrated station and the end station. For convenience indescribing the step-by-step operation of the system and the codingoperations at the various steps, the impulse or energized periods of theline circuit will be referred to as the on periods and the space periodsbetween impulses (deenergized periods of the line) will be referred toas the o periods.

Control oflice equipment.-The control office (Figs. 1A and 13) includesa quick acting line relay F and a quick acting line repeater relay FP,the former repeating the impulses applied to the line circuit and thelatter repeating the operations of relay F during a cycle of operations.Slow acting relays SA, SB and SC are picked up in sequence at thebeginning of each cycle and are dropped out in sequence at the end ofeach cycle. Relay SA has such slow acting characteristics that it doesnot drop between successive on periods during a cycle, since these onperiods follow each other at a sufficiently rapid rate to intermittentlyenergize relay SA (by the intermittent operation of relay FP), so thatit does not have time to drop between periods of its energizaion. RelaySB is a direct repeater of relay SA and relay SC is a direct repeater ofrelay SB, consequently these two relays remain picked up as long asrelay SA is picked up.

The impulses of a cycle effect the step-bystep operation of the steppingrelay bank, comprising stepping relays IV, 2V, 3V, 4V and LV and ahalf-step relay VP. This stepping relay bank is arranged so that aseparate stepping relay is picked up during each off period and thehalf-step relay shifts its position, alternately picking up anddropping, during each on period.

Impulse and impulse timing relays IE, 2E and 3E are controlled by thestepping relay bank in such a way that the impulses in the line circuitare made abnormally short or normally long as determined by whether ornot code sending relay PF is picked up or not respectively at each step.Relays lE, 2E and 3E also time the off periods by making them abnormallylong or normally short as determined by whether or not code sendingrelay P13 is picked up or not respectively at each step. An off periodis made abnormally long by including the drop away times of relays PTand PB, as will be more specifically pointed out in the detaileddescription. An on period is made abnormally short by picking up relayPF and consequently opening the line without waiting for the IE, 2E and3E operations.

Polarity control relays PC and NC are for the purpose of applying andimpulses respectively to the line circuit in accordance with selectedcodes. Code determining relay CD is one of a bank of such relays whichare so interconnected that the momentary depression of a starting buttonSTB picks up the associated start relay CH, which in turn picks up theassociated relay CD for initiating the system and selecting the code tobe applied during the resulting cycle. The interconnection of the CD andCH relays is such that the rapid successive operations of a plurality ofstarting buttons are stored, but only one CD relay is permitted to bepicked up at any one time. Since this feature is immaterial to anunderstanding of the present invention it is not shown in detail, ithaving been completely disclosed in the prior application of N. D.Preston, et al., Ser. No. 455,304, filed May 24, 1930, corresponding toAustralian Patent 1501 of 1931.

As typical of the control levers located in the control ofiice, switchmachine levers ISML and ZSML are shown. These levers are for the purposeof governing track switches ITS and ZTS as the illustrated fieldstation, which field station is assumed to be selected when relay CD ofFig. 1A is picked up, as determined by the particular connection of codejumpers l0 and II. It will be understood that additional levers forcontrolling the signals at the stations will be provided, but it is notbelieved necessary to complicate the drawings by showing this additionalequipment, since the operations controlled by levers lSML and ZSML aretypical of the operations controlled by additional levers.

Cycle controlling relay C is picked up to initiate a control cycle, thisrelay remaining up during each control cycle and, although notillustrated, it prevents a field start condition being initiated, aswell as controlling the energy for the polar control selection circuitsas will be pointed out in detail.

A track diagram comprising miniature track switches its and 215s,corresponding to track switches ITS and ZTS respectively at the fieldstation, and an OS lamp OSL, are provided, but control of theseminiature track switches and the OS lamp is omitted since no portion ofindication transmission is included in the present disclosure.

Field station equipment.The field station (Figs. 2A and 2B) includes aquick acting line relay F of the biased to neutral polar type and it isassumed that the polar contacts of this relay are operated to the rightwhen a impulse is applied to the line conductor and to the left (normalcondition as illustrated) when a impulse is applied to the lineconductor. Quick acting line repeating relay FP repeats the impulse inthe line circuit irrespective of their polarities. Slow acting relays SAand SE correspond to similar relays in the control oflice and are usedto define the bounds of an operating cycle, since they are picked up atthe beginning of each cycle and are dropped at the end of each cycle.

A stepping relay bank, including relays 1V 2V 3V 4V and VP, is providedand which operates in synchronism with the corresponding relays of thecontrol ofiice stepping relay bank. Executing relay EX is a last steprelay corresponding to relay LV in the control office, but as will bedescribed in detail it is for the purpose of executing stored controls.

Track switches [TS and ZTS are operated by switch machines ISM and 2SMrespectively in accordance with the switch controls transmitted over theline circuit, which selectively position switch machine relays ISMR and2SMR Suitable signals are also provided (not shown) for governingtrafiic over the illustrated track section and their control is inaccordance with suitable automatic signalling, in cooperation withmanual signalling controlled over the communication system. Since thissignal control is accomplished at the various steps of the cycle in amanner similar to that shown for controlling the switch machineoperation, it is believed unnecessary to illustrate this portion of thesystern.

Since indication transmission is not illustrated in the presentdisclosure, the usual track batteries and track relays and the usualswitch machine repeating relays and the like are not shown at theillustrated field station.

Relays CF CB MF and MB illustrated in 2A are for the purpose ofregistering and storing the lengths of the on and off periods inaccordance with the codes which determine the lengths of these periods.The detailed operation of these relays will be explained later. Duringthe transmission of polar controls for station selection the lengths ofthe on and off periods during these same steps are registered by relayssuch as ONS and OFS until the execution period after station selection,when the code stored on these storing relays is executed to the functioncontrol relays such as ISMR and 2SMR Station identification relay S andits cooperating stick relay SOS are shown in Fig. 2A to illustrate thestation selection feature, whereby controls are only transmittedto thefunction control relays after the station selection portion of the cycleand only at one station, which one station has its relay correspondingto S0 picked up.

OPERATION In the accompanying drawings the system is illustrated asbeing in its normal condition, from which it may be initiated for thetransmission of controls by the operation of starting button STB (seeFig. 1A). The two-wire line circuit is normally energized with negativepotential applied to the line conductor so that line relay F in thecontrol office is picked up and the polar line relays at the stationshave their polar contacts positioned to the left. The normally energizedline circuit provides means whereby the system may be initiated from afield station for the transmission of indications (not shown in thepresent disclosure), by opening the normally energized line circuit forregistering a field start in the control office by dropping normallypicked up relay F, as shown, for example, in the British Patent No.425,925 dated November 20, 1932.

A cycle of operations for the transmission of controls is started byquickly changing the negative line energization to a positive lineenergization, which registers in the control office and at the variousfield stations the condition that the following cycle is for thetransmission of controls.

Normal condition. The line circuit is normally energized over a circuittraced from the terminal of line battery LB (Fig. 1A), back contact l2of relay PC, front contact I3 of relay NC, return conductor l4, backcontact 200 of relay LO at the end station, line conductor H4, windingof relay F line conductor H5, winding of relay F, conductor l5, backcontacts 61, 66 and 65 of relays PF, PB and IE respectively, frontcontact 64 of relay 2E, back contact l6 of relay 3E, front contact I! ofrelay NC and back contact 3 of relay PC, to the terminal of battery LB.This negative line energization actuates the line relays as abovedescribed.

Relay 2E in the control office is normally energized over an obviouscircuit completed at back contact IQ of relay E. Relay PT in the controlofiice is normally energized over an obvious circuit completed at backcontact 28 of relay PB. Relay NC in the control office is normallyenergized over a circuit extending from back contact 2i of relay C, backcontact 22 of relay SC and winding of relay NC, to

Relay MB at the field station is normally energized over an obviouscircuit completed at back contact I09 of relay CB Relay CF at the fieldstation is normally energized over an obvious circuit completed at backcontact llll of relay FP All other neutral relays are normallydeenergized and it will be understood that the mag stick relaysillustrated in Fig. 2B, have their contacts illustrated in their righthand positions,

because of the construction of these relays whereby they maintain theircontacts in their last operated positions after the associated relaysare deenergized.

Manual start.The operation of button STB for initiating a control cyclecloses an obvious circuit for picking up relay CH. Relay CH closes astick circuit for itself extending from back contact 22 0f relay CD,front contact 23 and winding of relay CH, to Relay CD is picked up overa circuit extending from back contact 25 of relay SB, back contact 25 ofrelay LS, front contact 26 of relay CH and lower Winding of relay CD, toRelay CD closes a stick circuit for itself extending from back contact2'! of relay LV, conductor 28, winding of relay LS, front contact 29 andupper winding of relay CD, to

The opening of back contact 22 of relay CD deenergizes and drops relayCH. Relay LS is picked up over the stick circuit above described forrelay CD and relay LS in turn opens the pick up circuits for other CDrelays at back contact 25, so that other stored office start conditions,manifested by other CH relays being picked up, are ineffective to pickup the associated CD relays during this cycle of operations.

Relay C is picked up over a circuit extending from back contact 24 ofrelay SB, front contact 25 of relay LS and winding of relay C, todescribed normally energized circuit of relay NC at back contact 2|,which releases relay NC. Relay PC is picked up over a circuit extendingfrom front contact 2I of relay C, conductor 35, back contacts 3|, 32, 33and 34 of relays 4V, 3V, 2V and IV respectively, conductor 35 andwinding of relay PC, to

The dropping of relay NC and the picking up of relay PC reverses theconnection from battery LB to the line circuit, so that this line is nowenergized with a positive potential by way of pole changing contacts I2,I3, IT and I8. This quick reversal of "current in the line circuit iseffective to momentarily drop relay F, but this has no effect on thecontrol ofiice circuits because the cycle demarking relays SA, SB and SCare not yet picked up so that the operation of the relay F is notrepeated by the relay FP. Likewise the polar contacts of relay F areshifted to the right and its effect on the field station circuits willbe later described.

Relay FP in the control ofilce is picked up over a circuit extendingfrom front contact 35 of relay PC, conductor 36, front contact 37 ofrelay F and winding of relay FP, to Relay SA is picked up over a circuitextending from front contact 35 of relay PC, conductor 36, front contact38 of relay FP, conductor 39 and winding of relay SA, to Relay SAcompletes a stick circuit for relay C which includes front contacts I3and 93.

Relay SB is picked up over an obvious circuit completed at front contact45 of relay SA and relay SC is picked up over an obvious circuitcompleted at front contact 24 of relay SB. The opening of back contact22 of relay SC opens the above described normally energized circuit forrelay NC, so that this circuit will not be completed at the end of thecycle until relay SC is dropped.

Referring to the field station, relays S and SOS are picked up over acircuit extending from back contact I02 of relay IV conductor I83,contact I04 of relay F in its right hand dotted position, conductor I05,back contacts I516, Ifil, I08 and I09 of relays 4V 3V 2V and IVrespectively, conductor HE! and upper windings of relays SOS and S0 toRelay FP is picked up over a circuit extending from contact III of relayF in its right hand dotted position, front contact I I2 of relay S0 andwinding of relay FP to Relay SA is picked up over an obvious circuitcompleted at front contact H3 of relay FP and relay SB is picked up overan obvious circuit completed at front contact H6 of relay SA The aboveoperations effect the conditioning of the control office and fieldstation circuits so that the following impulses are effective to operatethe stepping relay banks in synchronism. It will be understood that thesame operations as described in connection with the illustrated fieldstation, take place at other field stations connected to the linecircuit.

Line impulsing and stepping relay operations.--Although the descriptionof the impulsing and stepping operations will be more particularlydirected to Figs. 1A and IE, it will be understood that similar steppingoperations take place at the field station illustrated in Figs. 2A and2B and at other stations along the line. Contacts MI and I42 of relay FPcorrespond to contacts 4| and 42 of relay FP in the oifrce and thedotted line associating contacts I4I and I42 with the field stationstepping relay bank indicates that this bank of stepping relays iscontrolled in the same manner that the stepping relay bank in thecontrol ofiice is controlled by contacts 4! and 42. Therefore it isbelieved unnecessary to illustrate or describe the operation of thefield station stepping relay bank in detail.

Relay VP is picked up in response to the picking up of relay SC over acircuit extending from front contact 43 of relay SC, conductor 44, frontcontact 4I of relay FP, back contact 45 of relay IV and winding of relayVP, to A first stick circuit for relay VP is completed which extendsfrom on conductor 44, front contact 45 of relay VP, back contact 45 ofrelay IV and winding of relay VP, to

Relay IE is now picked up over a circuit extending from front contact 4?of relay SC, conductor 36, back contacts 48, 49, 50 and EI of relays 4V,3V, 2V and IV respectively, front contact 52 of relay VP, conductor 53and winding of relay IE, to The picking up of relay IE deenergizes relay2E at back contact I 9 and relay 2E drops after a period of timedetermined by its slow acting characteristics. The dropping of relay 2Ecloses an obvious circuit for picking up relay 3E at back contact 54.

The picking up of relay 3E marks the end of the conditioning period andthe beginning of the first off period, by deenergizing the line circuitat open back contact It. The deenergization of the line effects thedropping of relays F and F and because of open front contact 3! of relayF and open polar contact III of relay F relays PP and FP are dropped.

A second stick circuit is now closed for relay VP extending from frontcontact 43 of relay SC, conductor 44, back contact 4| of relay FP, frontcontact 55 and winding of relay VP, to Relay IV is now picked up over acircuit extending from on conductor 44, back contact 42 of relay FP,front contact 56 of relay VP, back contacts and 58 of relays 4V and 2Vrespectively and winding of relay IV, to Relay IV closes an obviousstick circuit for itself at its front contact 59. During the followingoperation, when relays 2V, 3V, 4V and LV are picked up in sequence,similar stick circuits are closed at their front contacts 63, GI, 62 and63 respectively.

The picking up of relay IV deenergizes relay IE because the abovedescribed energizing circuit for this relay is now open at back contact5I. The dropping of relay IE effects the picking up of relay 2E becauseof closed back contact I9 and the picking up of relay 2E effects thedropping of relay 3E because of open back contact 54.

This marks the end of the first off period and the beginning of thefirst on period by again energizing the line circuit at back contact I5of relay 3E, completed through front contact 54 of relay 2E and. backcontacts 65, 65 and 6'! of relays IE, PB and PF respectively. Theenergization of the line circuit effects the picking up of relays F, F,FP and FP over the previously described circuits. Relay VP is nowdropped because its first stick circuit is open at back contact 45 ofrelay IV and its second stick circuit is open at back contact 4| ofrelay PP. The dropping of relay VP again completes the pick up circuitfor relay IE, previously described but now extending through backcontact 52 of relay VP and front contact 5I of relay IV. The picking upof relay IE and the consequent opening of its back contact I9 dropsrelay 2E and the closure of its back contact 54 picks up relay 3E.

This marks the end of the first on period and the beginning of thesecond off period by deenergizing the line circuit at open back contactl6. Relays F, FP, F and FP are released as before and relay 2V is pickedup over a circuit extending from on conductor 44, back contact 42 ofrelay FP, back contact 56 of relay VP, back contact 68 of relay 3V,front contact 69 of relay IV and winding of relay 2V to The picking upof relay 2V deenergizes relay |E by opening the circuit at back contact50. The dropping of relay |E again picks up relay 2E by way of backcontact l9 and the picking up of relay 2E deenergizes relay 3E becauseof open back contact 54'.

This marks the end of the second off period and the beginning of thesecond on period by again energizing the line, which again picks uprelays F, FP, F and PP. Relay VP is now picked up over a circuitextending from on conductor 44, front contact 4| of relay FP, backcontact 10 of relay 3V, front contact ll of relay 2V and winding ofrelay VP, to Relay VP again closes its first stick circuit as previouslydescribed and relay |E is picked up by means of the circuit completed atfront contact 52 of relay VP and front contact 55 of relay 2V. Relay 2Eis now released because of openback contact l9 and relay SE is picked upbecause of closed back contact 54.

This marks the end of the second on period and the beginning of thethird off period by again deenergizing the line circuit, which in turndrops. relays F, FP, F and PP. The second stick circuit for relay VP isagain completed and relay 3V is picked up over a circuit extending fromon conductor 44, back contact 42 of relay FP, front contact 55 of relayVP, back contact 5! of relay 4V, front contact 53 of relay 2V andwinding of relay 3V, to Relay |E is now released because of open backcontact 49 of relay 3V, relay 2E is now picked up because of closed backcontact H] of relay IE and relay 3E is now dropped because of open backcontact 54 of relay 2E.

This marks the end of the third off period and the beginning of thethird on period by again energizing the line circuit, which in turnpicks up relays F, FP, F and FF. Relay VP is again released because itsfirst stick circuit is open at back contact if! of relay 3V, and itssecond stick circuit is open at back contact 4| of relay FP. Relay |E isagain picked up because its circuit is now complete at back contact 52of relay VP and front contact 49 of relay 3V. Relay 2151 is released andrelay 3E is picked up because of open back contact 9 and closed backcontact 54- respectively.

This marks the end of the third on period and the beginning of thefourth o-fi period by again deenergizing the line circuit, which in turndrops relays F, FP, F and FP Relay 4V is now picked up over a circuitextending from on conductor 44, back contact 42 of relay FP, backcontact 55 of relay VP, front contact 68 of relay 3V and winding ofrelay 4V, to Relay IE is now released because of open back contact 48 ofrelay 4V, relay 2E is picked up because of closed back contact N ofrelay E and relay 3E is released because of open back contact 54 ofrelay 2E.

This marks the end of the fourth off period and the beginning of thefourth on period by again energizing the line circuit, which iseffective to pick up relays F, FP, F and FE", Relay VP is now picked upover a circuit extending from on conductor 44, front contact 4| of relayFP, front contact 12 of relay 4V and winding of relay VP to The firststick circuit for relay. VP is again closed and relay IE is picked upbecause its circuit is completed at front contact 52 of relay VP andfront contact 48 of relay 4V. Relay 2E is released because of open backcontact I9 and relay SE is picked up because of closed back contact 54.

This marks the end of the fourth on period and the beginning of theclearing out off period by deenergizing the line circuit, which in turndrops relays F, FP, F and PP. Relay LV is now picked up over a circuitextending from on conductor 44, back contact 42 of relay FTP,

front contact 56 of relay VP, front contact 51 of relay 4V and windingof relay LV, to The picking up of relay LV effects the release of relaysCD and LS because of open back contact 21 of relay LV.

The circuit for relay IE is not controlled by relay LV, as it was withthe previous stepping relays, therefore relay IE is not dropped duringthis off period to cause the picking up of relay 2E and the dropping ofrelay 3E for again energizing the line. This makes the clearing out offperiod extremely long and, because relay FP remains down, the energizingcircuit for relay SA is held open for an extremely long period at openfront contact 38, which allows relay SA to drop. The dropping of relaySA and the consequent opening of its front contact 4|] releases relay SBand the opening of its front contact 24 releases relay SC. Relay SCremoves energy from the stick circuits of the stepping and half-steprelays at open front contact 43, so that these relays are released.

Relay IE is also released because of open front contact 41 of relay SC,relay PC being down at this time with its front contact 35 open. Thedropping of relay IE picks up relay 2E because of closed back contact I9and the picking up of relay 2E drops relay 3E because of open backcontact, 54.

This marks the end of the clearing out off period and the beginning ofthe normal on period by again normally energizing the line. Thisenergization is negative because relay C was dropped during the clearingout off period, by the opening of its stick circuit at front contact 13of relay SA andthe dropping of relay C effected the release of relay PCor NO (which ever was picked up by the last code), by the opening offront contact 2|. Relay NC is picked up when relay SC drops to close itsback contact 22, which again completes the normal energizing circuit forrelay NC. This negative energization of the line again picks up relay Fand positions the polar contacts of relay F to the left, which is thenormal condition of the system.

As above mentioned, the field station steps through the cycle in amanner similar to that described for the oifice. Relay EX however, ispicked up during the clearing out off period at the same time that relayLV picks up and by means of a similar circuit. Relay 5A is droppedduring the clearing out period because of open front contact 3 of relayPP and relay SE is dropped because of open front contact N6 of relay SAThe stepping and half-step relays are deenergized in a manner similar tothe deenergization of these relays in the control ofiice. Assuming thatthe station illustrated is the one selected during this cycle, relay S0will remain picked up throughout the cycle until the clearing outperiod'when it will be released by deenergizing its stick circuit atopen front contact ll! of relay SE The SOS relay will be selectivelyoperated and the SO relay will be maintained operated in a manner whichwill be described in connection with station selection.

Polarity selection of control impulsea-It has been described how thenormal negative energization of the line circuit is changed to apositive energization for conditioning the office and field stationcircuits in response to the initiation of a control cycle.

It will now be assumed that the system steps through the cycle aspreviously described and an explanation will be given of how thepolarity of each control impulse is determined.

Code jumper No. II in its illustrated position makes the first impulse(first on period) positive. This is because relay PC is energized duringthe preceding (first) olf period when relay iV picks up. In other words,the switching of contact 30, of relay IV from its back to its frontpoint switches the on conductor 30 from conductor 35, by way ofconductor 14, front contact 15 of relay CD, jumper l l, PC bus andwinding of relay PC, to With relay PC up and relay NC down, the line isenergized with a positive impulse by way of pole changing contacts l2,23, If and I8 and over the circuit including the line and returnconductors as previously described.

In the event that jumper l is connected in its alternate dotted lineposition, then relay NC would be picked up and relay PC would be down,which would result in applying a negative impulse to the line circuit.

When relay 2V is picked up during the second off period, the polarity ofthe second impulse is determined by the connection of code jumper l6 andas illustrated in Fig. 1A, relay NC will be picked up over a circuitextending from front contact 2! of relay C, conductor 30, back contacts3| and 32 of relays 4V and 3V respectively, front contact 33 of relay2V, conductor 16, front contact ll of relay CD, jumper Ill, NC bus andwinding of relay NC, to

In the event that jumper H3 is in its alternate dotted line position,then relay PC would be picked up during the second off period for makingthe second impulse positive instead of negative. Although only two codejumpers are shown, it is believed that the typical example illustratedand described is suificient to indicate how the selection may be made onadditional steps of the cycle, for rendering the impulses in the linecircuit positive or negative, as determined by the code jumperconnections selected by the particular CD relay which is picked up.These polar impulses are determined for the third and fourth steps (whenthese steps are used for applying polar impulses to the line), byselections No. 3 and No. 4 made at front contacts 32 and 3! of relays 3Vand 6V respectively.

It will also be understood that, in the event of the station selectionimpulses being controlled on the first two steps of the cycle asindicated in the drawings, function control impulses on additional stepsof the cycle can be made positive or negative, by extending the No. 3,No. 4 and the like channel circuits through front contacts of relay CDto control levers, which determine the polarity of these impulses intheir normal and reverse positions, in the same way that they aredetermined by the two connections of the code jumpers. In the presentdisclosure, however, it is assumed that station selection is effected bythe polarity of the first two control impulses.

From the above it will be apparent that different polar codecombinations, comprising a choice of two per step may be used forselecting field stations and for controlling devices at the selectedstation.

Timing of control impuZses.The timing of the control impulses applied tothe line circuit is illustrated as being determined by the positions oflevers ISML and ZSML of Fig. LA, but it will be apparent from theprevious description, as Well as the description which follows, that thetiming of the impulses may be effective to provide station selectioncodes, since a choice of two is provided for each on period and anotherchoice of two for each off period.

In the previous description of the stepping operations it was assumedthat each off period was normally short. This because relay PB or Fig.1A remains down, so that the line is closed to mark the end of each offperiod by the dropping of relay 3E and the consequent closing of itsback contact i6. With levers iSML and 2SML in their illustratedpositions no energy is applied to the channel circuits to which they areconnected for picking up relay PB, thus the off periods coded by thesetwo levers are normally short.

To illustrate how an off period may be abnormally long it will beassumed that lever ISML is in its reverse position. When relay iV picksup during the first off period a circuit is closed for picking up relayPB which extends from lever iSlVlL in its left hand dotted position,front contact 18 of relay CD, conductor 15', front contact 86 of relaylV, back contact 8! of relay 2V, front contact 82 of relay VP, backcontact 83 of relay FP, conductor 54%, front contact 85 of relay PT andwinding of relay PB, to The picking up of relay PB opens the line atanother point, that is, back contact 85 of this relay so that theclosure of back contact i6 is ineffective to energize the line, sincefront contact 9 of relay F is open at this time.

Relay PB remains picked up and the line remains open until slow actingrelay PT drops and, by opening the circuit of relay PB at front contact35, relay PB drops and closes up the line. Due to the time intervalintroduced by the release time of relays PT and PB, the off period ismade abnormally long.

It will be observed that the dropping of relay PB again picks up relayPT because of closed back contact 28 and that the closure of frontcontact 85 again picks up relay PB. This line is not opened by theopening of back contact 56 this time, because relay F is up which closesa bridge path around contact 66 at front contact 9.

In the previous description the on periods were normally long becauserelay PF was not picked up, thus the end of each on period was notmarked until relay 3E picked up, which, because of the time intervalintroduced by the slow dropping of relay 2E during each on period,results in these on periods being normally long.

To illustrate how an on period is made abnormally short, it will beassumed that lever ESML is in its reverse position. With relay lV pickedup, a circuit is closed for picking up relay PF during the first onperiod, when relay VP drops, which circuit extends from contact of leverZSML in its reverse position, front contact 85 of relay CD, conductorSi, front contact 83 of relay lV, back contact 89 of relay 2V, backcontact 9!] of relay VP, front contact of relay FP, conductor 92 andwinding of relay PF, to

The picking up of relay PF, immediately after the shifting of the VPrelay, opens up the line circuit at back contact 61 without waiting forrelay IE to pick up, relay 2E to drop and relay 3E to pick up foropening the line as previously described. This quick opening of the linecircuit terminates the on period very shortly after the shift of the VPrelay, which makes the on period comparatively short.

From the above examples it is believed apparent that any of the four offand on periods of the previously described cycle can be made short orlong for coding the control impulses, either for station selection 'orfor the transmission of controls to the selected station, as determinedby the separate channel circuit selections made as illustrated in Fig.1B, having the legends 01f controls short or long and on controls shortor long applied thereto.

Station selection and transmission of controlsr-It was previouslydescribed how relays and S08 were picked up at the start of the cycle.With the first impulse as determined by jumper II and the second impulseas determined by jumper Ill, relay F is positioned to the right duringthe first on period and to the left during the second on period. Thepicking up of relay SB during the conditioning on period establishes astick circuit for relay SO8 extending from front contact III of relay SEfront contact H8 of relay FP front contact I IQ and lower winding ofrelay SOS to A stick circuit is also closed for relay S0 extending fromfront contact III of relay SB front contact I29 of relay SO8 frontcontact I EI and lower winding of relay S0 to The dropping of relay FPduring the first off period drops relay $08 by opening the abovedescribed stick circuit at front contact I I8. At the same time thatthis stick circuit is opened, and before relay SOS drops, another stickcircuit is closed for relay S0 extending from front contact III of relaySE back contact II 8 of relay FP front contact I2I and lower winding ofrelay S0 to During the first on period the actuation of the polarcontacts of relay F to the right completes a pick up circuitfor relaySOS extending from front contact I22 of relay S0 contact IE4 of relay Fin its right hand dotted position, conductor I05, back contacts I86, I67and I08 of relays 4V 3V and 2V respectively, front contact I09 of relayIV code jumper I23 in its full line position, conductor H0 and upperwindings of relays SOS and $0 to It will be observed that this pick upcircuit for relay SOS is dependent on relay SO being picked up, thisbecause relay IV has its back contact I92 open.

It will also be observed that this pick up circuit for relay SOScomprises an energizing and holding circuit for. relay S0 before relayFP drops and breaks the stick circuit for relay SO3 at front contactII8. Therefore, if the code jumper I23 is in its alternate dotted lineposition, relay SOS cannot be picked up and the stick circuit for relayS0 by way of front contact I28 of relay SOS is incomplete, so that thecontinued energization of relay S0 is made dependent on this selectingcircuit including jumper I23. If this selecting circuit is incompleteand relay SOS is not picked up, then when relay FP opens its backcontact H8 the stick circuit including this back contact for relay S0 isbroken and this latter relay is dropped out.

In the example assumed, jumper I23 in' its full line position maintainsrelay S0 picked up and allows relay SO3 to'be picked up, after which thestick circuit for relay S0 is completed through front contacts I20 andI2I and the stick circuit for relay SOS is completed through frontcontacts H8 and II 9. This illustrates how the selection is made duringthe first on period and it will now be pointed out how relay S0continues to be energized in response to the negative code applied tothe line circuit during the second on? period.

. During the second off period, relay S0 is stuck up because of theclosure of back contact N8 of relay F12 and relay SOS is dropped outbecause of open front contact H8. Relay 2V is picked up during thesecond off period and with relay F actuated to the left the abovedescribed circuit through the upper windings of the S08 and S0 relays iscomplete and may be traced from front contact I22 of relay S0 contactI94 of relay F in its left hand position, conductor I24, back contacts I25 and I25 of relays dV and 3V respectively, front contact I21 of relay2V jumper I28 in its full line position and conductor III! to the upperwindings of the SO and SOS relays. Relay SOS is picked up and stuck upand relay S0 is stuck up as previously described. 'It will be obviousthat, with jumper I28 in its alternate dotted line position, a positiveimpulse is required for the second on period to complete the abovedescribed circuit.

With the station selection made on the first two steps, then a permanentstick circuit (complete throughout thecycle) is completed during thenext off period when relay 3V picks up, which stick circuit extends fromfront contact .I II of relay SB conductor I29, front contact I38 ofrelay 3V back contact IBI of relay EX conductor I32, front contact I INand lower windingof relay S0 to Since the polar impulses of the firsttwo steps are used for station selection, it becomes necessary to storethe code comprising the short and long .off and on periods of these twosteps, so that these codes may be executed to the function controlrelays after the station is selected and only at the selected station.

Lever ISML in its normal position determines that the first off periodwill be normally short as previously described. This means that relay FPat the station will be picked up for again energizing relay CB at frontcontact I95, before this relay had time to drop after its deenergizationat open front contact Iill. It will be obvious of course that relay CBis picked up dur ing each on period and is only dropped out during thesucceeding off period when this off period is abnormally long.

' 'The picking up of relay CB during the previous on period opens thepick up circuit of relay MB at back contact I00, but relay MB is stuckup over a circuit including front contacts I 33 and I34 of relays FP andMB respectively. During the short 0 period, both the pick up and stickcircuits of relay M13 remain open at contacts I 33 and IIII] so thatthis relay drops and, since relay CB does not drop out, relay MB remainsdown. Then during the succeeding on period the condition of relay M28 istransferred by completing a circuit for the lower winding of relay OF'Swhich may be traced from front contact I 35 of relay Sl3 front contactI36 of relay S0 front contact I31 of relay F1 back contact I38 of relayMB conductor I39, back contacts I 43, I44 and I45 of relays 4V 3V and 2Vrespectively, front contact I46 of relay IV and lower winding of relayCF8 to Since relay OFS is of the mag stick type the energization of itslower winding positions its polar contacts to the right and they staythere until the end of the cycle. During the executing period switchcontrol relay ISMR is energized to position its polar contacts to theright by means of a circuit extending from back contact I4! of relay SAfront contact I48 of relay 8B front contact 49 of relay S0 conductorI50, front contact I55 of relay EX contact I5I of relay OFS in its righthand position and upper winding of relay ISMR to Polar contact I52 ofrelay ISMR. in its right hand position, controls the operation of switchmachine ISM to its normal position.

In the event that lever ISML is in its reverse position, then the firstoff period would be abnormally long allowing relay CB to drop out duringthis off period for picking up relay MB by Way of back contact I50,after the stick circuit of relay MB is broken at front contact I33 ofrelay FP During the next succeeding on period the stick circuit forrelay MB is completed at front contact I33 before relay CB is againpicked up. This condition is transferred during the above mentionedsucceeding on period by completing a circuit extending from at frontcontact I35 of relay SB and extending through front contact I38 of relayMB conductor I53, back contacts I54, I55 and I56 of relays 4V 3V and 2Vrespectively, front contact I5'I of relay W and upper winding of relayOFS to The energization of the upper winding of this relay positions itspolar contacts to the left for energizing the lower winding of relayISMR. during the executing period, which positions its polar contacts tothe left for operating switch machine ISM to its reverse position.

With lever 2SML in its normal position the first on period is normallylong as already described. Because relay FP remains picked up with itsback contact IBI open for a comparatively long interval, relay CF, dropsand closes a circuit for picking up relay MF extending from back contactI58 of relay CF and winding of relay ME to During the next succeedingoff period the dropping of relay FP completes a stick circuit for relayME by way of front contact I59 of relay MF before its pick up circuit isopened by the picking up of relay CF This condition is transferredduring the above mentioned succeeding off period by energizing the upperwinding of relay ONS over a circuit extending from front contact I35 ofrelay SE front contact I36 of relay S0 back contact I31 of relay FPfront contact I60 of relay MF conductor IBi, back contacts I62, I63 andI64 of relays 5V 3V and 2V respectively, front contact I65 of relay IVand upper winding of relay ONS to Polar contact I66 of relay ONS ispositioned to the right and an executing circuit is closed at the end ofthe cycle for energizing the lower Winding of relay ZSMR by way ofcontact I66 in its right hand position. Polar contact I61 of relay ZSMRcontrols the operation of switch machine ZSM to its normal position.

With lever ZSML in its reverse position, the first on" period is madeabnormally short and relay C? does not have time to drop before relay FPcloses its back contact IIJI and reenergizes this relay. Relay MP isreleased (if up) by the opening of its stick circuit at back contact I33and is not again picked up because its pick up circuit is open at backcontact I58. During the succeeding off period the lower winding of relayCNS is energized over a circuit extending through back contact I60 ofrelay MF conductor I68, back contacts I69, I10 and [ll of relays 5V 3Vand 2V respectively, front contact I12 of relay IV and lower winding ofrelay ONS to Relay ONS operates its polar contacts to the left andduring the execution period a circuit is completed through contact I66in its left hand dotted position for energizing the upper winding ofrelay 2SMR which positions polar contact I51 to the left for operatingswitch machine 2SM to its reverse position.

It is believed that the above examples are sufficient to indicate howthe various code combinations are provided at any number of steps, asdetermined by the capacity of the system to which the present inventionis applied. It will be understood that, when a station is dropped outduring the station selection portion of a cycle by the dropping of itsassociated SO relay, stepping does not take place at such stationbecause the associated FP relay has its circuit maintained open at afront contact such as front contact H2 of relay S0 It will furthermorebe observed that relay FF is not energized during the normal conditionof the system, because contact III of relay F in its left hand positionleads to open contact I13 of relay SE but during the cycle front contactH3 is closed, so that relay FF is operated irrespective of the positionof polar contact ill of relay F as long as front contact H2 remainsclosed.

Having thus described one specific embodiment of a centralized trafficcontrolling system, it is desired to be understood that the particulararrangements illustrated and suggested are only typical of applicantsinvention and are not intended to indicate the exact circuit design andspecific arrangement of parts necessary to carry out the features of theinvention. This particular form has been chosen to facilitate in thedisclosure rather than to limit the number of forms which the inventionmay assume and it is furthermore to be understood that variousmodifications may be made in order to meet the various problemsencountered in practice, the system may be varied in the number of fieldstations and the amount of apparatus at each field station may be variedto suit local conditions, and any desired organization for theregistration of a field station in the control office and thetransmission of indications therefrom may be provided, all without inany manner departing from the spirit or scope of the present inventionexcept as limited by the appended claims.

What I claim is:

1. In a remote control system; a line circuit; a source of currentconnected to said line circuit; a polar line relay included in said linecircuit; an impulse relay controlled by said line relay; means for attimes opening and closing said line circuit and reversibly connectingsaid source of current thereto for producing a series of time spacedpolar impulses having polar characters in accordance with differentcodes, said line relay being intermittently operated by said time spacedimpulses dependent upon their polarity and said impulse relay beingoperated irrespective of their polarity; means for prolonging selectedones of said impulses and time spaces of said series; two slow releaserelays each having a release time less than said prolonged impulses andtime spaces and greater than impulses and Iii) time spaces notprolonged; a pick up circuit for a first one of said slow release relayscontrolled by a back contact of said impulse relay; a pick up circuitfor a, second one of said slow release relays controlled by a frontcontact of said impulse relay; a plurality of devices; a first registermeans selectively controlled 'by the polarity of said series of timespaced impulses so as to be rendered active only in response to aparticular one of said difierent codes; a second register meansselectively positioned by said first slow relay during said impulses ofsaid seriesinaccordance with lengths of such impulses; a third registermeans selectively positioned by said second slow relay during timespaces between impulses of said series in accordance with the length ofsuch spaces; and means for selectively controlling said plurality ofdevices at the end of said time spaced impulses in accordance with saidsecond and said third register means only if said first register meansis rendered active.

2. In a remote control system, control office and a field stationconnected by a single line circuit, transmitting means ,in said officefor transmitting a series of time spaced positive and negative impulsesover said line circuit, said impulses and said time spaces of saidseries all being selectively varied in length in accordance withcontrols to be transmitted and the polarity of the same impulses of saidseries being selected in accordance with a predetermined code pattern,step-by-step means at said station for operating through a cycle ofoperation in response to said impulses, means at said station forregistering the length of the impulse and the length of the time spacefor each step, selecting means at said station distinctively conditionedonly providing the polarity of said impulses for several steps conformsto a particular code pattern, a plurality of electro-responsive devicesat said station, and means for controlling said electro-responsivedevices at the end of an operating cycle in accordance with theregistered lengths of said impulses and time spaces only providing saidselecting means has been distinctively conditioned, whereby thereception of controls and distinctive conditioning in accordance with acode can be simultaneously accomplished.

3. In a remote control system, a control mice and a plurality of fieldstations connected by a single line circuit, means at said office fortransmitting a series of time spaced positive or negative impulses oversaid line circuit, means at said office for varying the lengths of saidimpulses and the time spaces between such impulses in accordance withthe controls to be transmitted to a particular station, said means alsoacting to determine the positive or negative polarity of the impulses inaccordance with a code pattern assigned to that station, means at eachof said stations for registering the lengths of the impulses and thelengths of the time spaces between said impulses, selecting means ateach of said stations distinctively conditioned only provided saidimpulses conform in polarity to the code pattern assigned to thatstation, a plurality of electroresponsive means at each station, andmeans at each station for controlling said electro-responsive means atthat station in accordance with the registered lengths of the impulsesand time spaces at the end of said series of impulses only provided theselecting means at that station has been distinctively conditionedduring such series of impulses by their positive and negativecharacteristics conforming to the code call for that station.

4. In a remote control system; a control office and a plurality of fieldstations connected by a line circuit; transmitting means at said controlofiice for transmitting different series of time spaced current impulsesof selected polarities over said line circuit, the polarities of anygiven series being dependent upon the particular station to be selectedfor the reception of controls during that series of impulses; means atsaid control omce acting on said transmitting means during any givenseries for varying the lengths of said impulses and the time spacesbetween such impulses or" that given series in accordance with thecontrols for the field station to be selected for that series; storingmeans at each of said field stations for receiving and distinctivelyregistering, only when rendered effective, the lengths of the impulsesand the lengths of the time spaces between the impulses of any series;station selecting means at each of said field stations responsive onlyto the polarity of the impulses of a particular one of said differentseries for rendering erfective said storing means at that station; aplurality of power-operated devices at each of said field stations; andmeans at each of said field stations dependent upon the response of saidstation selecting means at that station to its particular one of saiddifferent series for distinctively operating the power-operated devicesat that station in accordance with the lengths of the impulses and thelengths of the time spaces for that series as registered in said storingmeans.

5. In a remote control system; a control ofiice and a field stationconnected by a line circuit; transmitting means at said control officefor transmitting a plurality of time spaced current impulses over saidline circuit; means at said office for acting on said transmitting meansto vary the polarity of said plurality of impulses, the lengths of saidplurality of impulses, and the time spaces between said plurality ofimpulses; receiving means at said station responsive to said pluralityof impulses on said line circuit and acting to store the lengths of saidimpulses and the time spaces between such impulses when such receivingmeans is rendered effective; selecting means controlled by the polarityof said plurality of impulses for rendering said receiving meanseffective; a plurality of devices at the field station; and means actingonly after all of said plurality of impulses have been received andtheir polar characteristics have controlled said selecting means fordistinctively and simultaneously controlling said devices. in accordancewith the lengths of said plurality of impulses and the lengths of saidtime spaces between such impulses as stored in said receiving means.

6. In a remote control system; a control office and a plurality of fieldstations connected by a single line circuit; a source of direct currentenergy in said control ofiice; transmitting means at said control officealone for timing and impressing series of time spaced impulses ofselected polarities on said line circuit from said source of energy;means at the control oflice acting on said transmitting means todetermine the relative short and long lengths of said impulses and therelative short and long lengths of the spaces between such impulses ofany given series in ac cordanoe with the controls to be transmitted tothe particular station selected for that series, said means also actingto determine the positive and negative polarities of said impulses inaccordance with the code assigned to that particular station; stationselecting means at each of said field stations rendered active at thebeginning of every series but maintained active during any given seriesonly if the polarities of the impulses of that series conform to thecode assigned that field station; storing means at each field stationfor registering the lengths of the impulses and the lengths of thespaces between said impulses of any given series only so long as saidstation selecting means is active during said series; a plurality ofdevices at each of said field stations; and means at each of said fieldstations for controlling said devices at that station in accordance withthe condition of said storing means at the end of any given series onlyif said station selecting means has been maintained active throughoutsaid series.

'7. In a remote control system; a control oifice and a plurality offield stations connected by a single line circuit; a plurality ofdevices at each of the several field stations, a plurality of controllevers in the control oifice for each of said field stations;transmitting means at said control office alone for timing andimpressing series of time spaced impulses of selected polarities on saidline circuit from said source of energy; a plurality of code determiningrelays in the control oifice respectively associated with the severalfield stations and effective, when rendered active, to cause saidtransmitting means during a particular series of impulses to becontrolled in accordance with the control levers for that associatedfield station to determine the relative short and long lengths of saidimpulses and the relative short and long lengths of the spaces betweensuch impulses of any given series for the particular station with whichsuch levers are associated, said code determining relay for anyparticular station also acting to determine the positive and negativepolarities of said impulses for the series in accordance with the codeassigned to that particular station; means associated with said codedetermining relays for allowing only one of the several code determiningrelays to be active during the same series of time spaced impulses;station selecting means at each of said field stations rendered activeat the beginning of every series of impulses but maintained activeduring any particular series only if the polarities of the impulses ofthat series conform to the code assigned to its field station; storingmeans at each field station for registering the lengths of the impulsesof any series and the lengths of the spaces between the impulses of anyseries only so long as said station selecting means is active duringsaid series; and means at each of said field stations for controllingsaid devices at that station in accordance with the condition of saidstoring means at the end of any given series providing said stationselecting means has been maintained active throughout the series byreason of the polarity of the impulses of such series conforming to thecode call of that station.

FREDERICK W. BRIXNER.

